Timer for electrical contacts



Jan. 1, 1924 1,479,498

. l. s. DEMENT TIMER FOR ELECTRICAL CONTACTS Filed April '7, 1919 I 2 l6 I0 I l 4 I? Z "To l| x4, 49 9 i 9 7T; r w A? J j 1 a INVENTOR. 13mm dirznc/w' ATTORNEY Patented Jan. 1, 1924.

UNITED STATES ISAAC S. DEMENT, F DAYTON, OHIO.

TIMER FOR ELECTRICAL CONTACTS.

Application filed April 7, 1919. Serial No. 288,136.

To all whom it may concern:

Be it known that I, ISAAC S. DEMENT, a citizen of the United States, residing at Dayton, inthe county of Montgomery and State of Ohio, have invented certain new and useful Improvements in Timers for Electrical Contacts, of which the following is a specification, reference being had therein to the accompanying drawing.

trical contacts, and it is desi ed more particularly for use with ignition circuits of automobile engines, but is not necessarily limited to that use.

One object of the invention is to provide a timer device which will positively make and break the several contacts in proper timed relation; and further, which will be of such a character and so constructed that there will be no lost motion between the parts due to wear or the loose fitting thereof.

It is also an object of the invention to provide a device of this kind which can be readily adjusted to advance or retard the 26 spark.

It is also an object of the invention to provide a device of this kind which will be very simple in its construction and operation and which can be produced at a relatively low cost.

In the accompanying drawings Fig. 1 is a sectional view taken on the line A-A of Fig. 2; and Fig. 2 is a sectional view taken on the line BB of Fig. 1.

In these drawings I have illustrated one embodiment of my invention and have shown the same as designed for use with a four-cylinder internal combustion engine, but it will be readily understood that the device can be easily constructed to accommodate it to engines comprising various numbers of cylinders, and that the construction may be modified without departing from the spirit of my invention.

In the particular embodiment of the invention here illustrated I have shown the same as comprising a base wall 1 which is preferably formed of insulating material, such as bakelite,and which is provided with a central bearing 2 in which is journaled a shaft 3 which serves to operate the timing device and which may be driven from the engine in any suitable manner and may be supported in any convenient place. Mounted on the base wall 1 and rigidly secured there- This invention relates to timers for electo is an annular gear 4 which is here shown as an internal gear. The gear is shown as insulated and is preferably formed of insulatlng material. In the present instance, the teeth are formed in the inner periphery of an annular ring of -insulating material, such as bakelite, which forms the body of the gear. Mounted about the gear 4 are a series of contacts 5 which are preferably secured in fixed positions relatively to the gear and correspond in number to the number of circuits in the ignition system, which are to be controlled, that is, the number of cylinders in the engine. These contacts may be of anyv suitable character and may be mounted in any suitable manner, but, as here shown, each contact comprises a pair of contact fingers extending inwardly from a body portion or head 6 which is seated inan opening 7 in a supporting structure 8, such as a ring of insulating material, which structure is rigidly secured to and, in the present instance, is formed integral with the gear 4. The outer end of the body portion of each contact is provided with a binding post 9 by means of which it may be connected in the circuit. The inner ends of the contact fingers 5 preferably project inwardly slightly beyond the inner periphery of the supporting structure 8 and are flared to facilitate their engagement with the movable contact member, as hereinafter explained.

A second gear 10 meshes with the annular gear 4 and, in the construction here illustrated, this second gear is in the form of an ordinary spur gear, preferably-formed of insulatin material, and of a diameter considemb y less than the diameter of the internal gear. This second gear is mounted within the internal gear and is permanently in mesh therewith, it being mounted for bodily movement about the axis of the shaft 3 and for rotatory movement about its own axis. The gear 10 is caused to travel along the gear 4 by means of the shaft 3 and it is preferably permanently connected with this shaft and arranged eccentrically to the internal gear. To this end I have shown the gear 10 as mounted on a wrist pin 11 carried by a crank arm 12 which is rigidly secured to the shaft 3. The length of the crank arm 12 is such that those teeth of the gear 10 which are in alinement with the arm 12 will mesh with the teeth of the internal gear. Consequently, as the crank arm rotates with the shaft 3 the 110 gear 10 will be carried about the internal gear 4: and the engagement of the teeth of the gear 10 with the teeth of the gear 4 will cause the former gear to be rotated about its individual axis. The gear 10 has connected therewith, and preferably rigidly secured thereto, a contact member which, in the present construction, comprises three contact arms 13, which are here shown as mounted on the side of the gear 10 and arranged to engage the fixed contact members 5 as the gear 10 travels about the internal gear. The gear 10 is of smaller diameter than the internal gear and the ratio of the two gears is such that'the number of teeth lying between any two of the contact arms 13 will be equal to the number of teeth lying between any two of the fixed contacts 5. Con sequently, the travel of the gear 10 along the internal gear will cause the contacts 13 to successively engage the fixed contacts 5,

the movement of the gear serving to,prop,

erly position each movable contact with relation to the fixed contact and to force the same into firm engagement therewith and to then positively separate the two contacts before the next movable contact engages, the next fixed contact. The movement is absolutely positive and there is no possibility of slippage or improper timing. Because of the fact that bodily forward movement is imparted to the gear 10 by the shaft 3, it will be apparent that the teeth of the gear 10 will always be in firm engagement with the teeth of the internal gear and that there will be no lost motion-or loose movement between the two gears which might interfere with the proper making and breaking of the con tacts or with the timing thereof.

It is desirable that some adjustment should be provided to permit of the spark being advanced or'ret-arded as may be desired and, to, accomplish this I have, in the present construction, shown the device as a whole as adjustable relatively to the shaft 3 so that the contact may be made at different periods during the rotation of the shaft 3, that is, a contact may be made at the instant that the shaft completes a rotation, terminating at a given point, or the contact may be made either slightly before or slightly after the completion of that rotation. This adjustment may be accomplished in any suitable manner and the device as a whole may be mounted in any manner which will permit this adjustment. A here shown, the shaft 3 forms the sole support for the timing device and the latter is held against movement from a fiXed position with relation to the shaft by means of its connection with an adjusting lever. Preferably, the ordinary spark adjusting lever on the steering wheel of an automobile is employed for ad justing the timing device and to this end a rod 14 is connected with the spark lever and invaaea with a projection or lug 15 rigidly secured to the "timing device. This connection is such that so long as the spark adjusting lever remains stationary the timing device will be held against movement, but any movement of the spark adjusting lever will be transmitted to the timing device.

The timing device is preferably enclosed in a metal casing and, as here shown, this casing comprises two parts 16 and 17 which embrace the opposite sides of the timing device. The edges ofthis casing must be supported out of engagement with the fixed contacts and T have here shown the gear structure, 4-8, as having circumferential rib 18 which is of a width slightly greater than the body portions 6 of the fixed con tact members and serves to interpose a rib of insulating material between each edge of the metal casing and the contact members.

The operation of the device will be readily understood from the foregoing description thereof, and it will beapparent that as the shaft 3 rotates the gear 10 will be caused to travel about the internal gear 4, thus causing the movable contacts to be moved positively into and out of engagement with the fixed contacts and, because of the intermeshing gears, therecan be no slip page of the parts and no improper timing, as the contacts are positively moved in a fixed relation to the movement of the shaft 3; There will be very little wear on the device, and such as there is will not interfere with its operation, as the bodily movement of thegear 10 serves to hold the teeth thereof firmly in engagement with the teeth of the gear 4 even though these teeth may be worn to such an extent that the two gears mesh very loosely one with the other. The device is exceedingly simple in its construction and operation, and can be ver easily maintained in an operative condition. Further, the adjustment of the device to ad vance or retard the spark is made in such a manner that it cannot interfere in any way with the proper timing of the movable contacts. lVhile I have shown and described one embodiment of my invention, 1 wish it to be understood that I do not desire to be limited to details of construction, as various modifications will occur to a person skilled in the art.

Having thus fully described my invention, what I claim as new and desire to secure by Letter Patent is:

1. In a device of the character described, an internal gear, a plurality of contacts spaced about said gear and each comprising a pair of yieldable fingers, a second gear meshing with said internal gear and arranged eccentrically thereto, means for imparting bodily movement to said second gear, and a plurality of contact fingers rigidl connected with said second gear and arranged to engage the respective pairs of yieldable fingers as said second gear travels about said internal gear.

2. In a device of the character described, an annular body having a series of radial recesses therein, contact members each comprising a pair of ieldable fingers mounted within the respectlve openings in said body member, an internal gear arranged concentrically with said body, a second gear meshing with said internal gear and arranged eccentrically thereto, means for imparting bodily movement to said second gear, and a plurality of contacts carried by said second gear and arranged to operatively engage the respective pairs of fingers as said second gear travels about said internal gear.

3. In a device of the character described, a shaft, a body supported by said shaft and comprising an "annular portion arranged concentrically to said shaft and having a plurality of openings therein, contact members each comprising a pair of yieldable fingers mounted in the respective openings, a crank arm secured to said shaft within said body, a second gear of smaller diameter than said internal gear mounted on said crank arm and adapted to travel about said internal gear, a contact member rigidly secured to said second gear and comprising a plurality of radial fingers arranged to engage between the resilient fingers of the respective first mentioned contacts as said second gear travels about said internal gear.

In testimony whereof, I aflix my signa ture hereto.

ISAAC S. DEMENT 

